A wet sauna is a traditional cabin you run with water on the hot stones, so the humidity rises in bursts and the heat feels softer and heavier than dry air at the same temperature. It is not a steam room and it is not a separate product line. Buying one well is mostly about the heater and how the cabin copes with moisture.
Wet sauna, steam room, and the confusion between them
Retailers use wet sauna loosely, and some mean a steam room by it. A steam room is a sealed tiled enclosure at saturated humidity fed by a generator. A wet sauna is a wooden cabin with a stove and stones, dry between ladles. If a listing shows tile and a generator you are looking at steam, whatever the heading says.
The heater and the stones
Water on the stones is the whole point, so the stone mass is the specification that matters. A heater holding a deep load of stones stores enough heat to turn several ladles into steam without the cabin going cold. A thin tray cools instantly. Ask what weight of stone the model takes, not just the kilowatt rating.
Wood, floor and venting
Run wet and the cabin takes water every session. Cedar, hemlock and thermally modified softwoods handle the cycling and stay cool against skin. The floor wants to shed water, which is why many cabins use duckboards over a sealed base. And you want an outlet vent that can clear humid air afterwards, or the cabin stays damp.
Cost against a dry setup
Running it wet costs almost nothing extra: the same heater, a bucket and a ladle. The cost sits at build time in the heater you choose and the venting you plan for. A cabin specified for wet use is a better cabin dry as well, so it is rarely worth buying a dry-only setup to save a little.
Questions people ask about wet sauna
Can I pour water on any sauna heater?
Only on a traditional heater designed for it, and only on the stones. Never on an infrared panel and never on an electric element that is not rock covered.
How wet does it actually get?
Briefly humid, then dry again. A ladle raises humidity for a minute or two. It never approaches a steam room, which sits saturated the whole session.
Does a wet sauna need a drain?
Not usually at home. The water that reaches the floor is small, and a duckboard over a sealed floor with ventilation is enough for most cabins.